A wheel-guiding forward axle spring strut is disclosed in U.S. Pat. No. 4,482,135.
Wheel-guiding spring struts are often mounted on the forward axle of passenger cars. Because the wheel is attached directly to the shock absorber cylinder, a torsion of the cylinder relative to the chassis occurs when the vehicle is steered. This torsion must be taken up by a pivot bearing.
The spring strut is supported by a ball bearing on the chassis. All forces (deflection amplitude-dependent spring forces and deflection speed-dependent shock absorber forces), which are generated in the spring strut, are directed through the bearing. For this reason, the bearing is loaded in compression as well as in tension and must take up high force peaks.
In order to maintain the bearing loads within acceptable limits, often only the spring and not the complete spring strut is supported by a pivot bearing. The rotational movement between the shock absorber cylinder and the shock absorber rod is, in this case, taken up by the seal of the shock absorber; that is, the shock absorber rod is connected directly to the chassis.
Taking up the rotation movement by the shock absorber is made possible by a rotationally-symmetrical configuration of the shock absorber piston and the shock absorber cylinder.
A separation of the spring rotation movement from the shock absorber rotational movement has been realized up to now only with helical spring struts. In this connection, reference can be made, for example, to U.S. Pat. No. 4,482,135 and the other state of the art referred to therein.
In air spring struts, up to now, all forces have been conducted via a single spring pivot bearing. In this connection, reference can be made to the article of Reimpel entitled “Fahrwerkstechnik: Stoβ-und Schwingungsdämpfer”, Vogel-Verlag (1989), page 229, as well as German patent publications 196 07 804 and 197 53 637. Such a pivot bearing must be designed to be correspondingly robust for the above-mentioned reasons. A separate configuration of spring pivot bearing and shock absorber pivot bearing could, up to now, not be realized because of sealing problems in the head region of the air spring.